WO1995004877A2

WO1995004877A2 - Internal combustion thermal engine comprising at least two opposed cylinders

Info

Publication number: WO1995004877A2
Application number: PCT/FR1994/000916
Authority: WO
Inventors: Pierre Edouard Dorges
Original assignee: Pierre Edouard Dorges
Priority date: 1993-08-09
Filing date: 1994-07-21
Publication date: 1995-02-16
Also published as: FR2708970A1; WO1995004877A3

Abstract

The invention concerns an engine, wherein the piston (6a, 6b) linked by pairs, through a rigid rod (7) form a running part moving in opposed cylinders (2a, 2b) aligned along a common axis. The transformation of the rectilinear reciprocating motion takes place, in a central crank-chamber (5), through one or several connecting rods (10a, 10b), located on either side of the rod (7), driving one or several cranks (12a, 12b), capable of being coupled on a common shaft (17) by gear or any other system. Only the rotating mechanical energy is transformed by the rod/crank system. The compression/expansion energy is directly by the rigid rod. That arrangement enables to separate by sealing partitions (18a, 18b) the crank-chamber (5) from the piston compartments (19a, 19b), which serve to compress fresh air before intake into the combustion chambers (B) through the pistons (6a, 6b). The gas path is simplified, the central part is maintained at room temperature. The burnt gas exhaust is ensured by the cylinder heads (3a, 3b) arranged at the ends of the cylinders (2a, 2b). The cool gases are never in contact with the hot gases, thereby improving performance. Fuel injection is carried out in the cylinder heads (3a, 3b) using compressed air pressure in the combustion chambers (B), the amount injected being mechanically and electronically controlled. The architecture of the engine enables easy control of the set of parameters ensuring proper non-polluting combustion with reduced fuel consumption.

Description

INTERNAL COMBUSTION HEAT ENGINE HAVING AT LEAST TWO OPPOSITE CYLINDERS

The invention relates to an internal combustion engine of the kind of those which comprise at least two opposite coaxial cylinders, and, in each cylinder, a reciprocating rectilinear piston, a connecting rod / crank system being provided to transform the movement. of each piston in a circular motion of an output shaft.

The invention relates more particularly, because it is in this case that its application seems to be of most interest, but not exclusively, internal combustion engines operating in a two-stroke cycle.

By the term "internal combustion engine" is meant in particular internal combustion engines, in particular petrol injection, and diesel type engines.

The object of the invention is, above all, to provide an internal combustion engine with high efficiency and the weight of which is reduced for a given developed power. We also want to reduce oil consumption and the corresponding pollution. According to the invention, an internal combustion engine, in particular with a two-stroke cycle, of the kind defined above, is characterized in that the pistons of two opposite cylinders are connected to each other by a rigid rod animated by same reciprocating rectilinear movement as the pistons, and at least one articulation ^" orthogonal to the axis of the rod, is provided on this rod for the end of a connecting rod, the other end of this connecting rod being articulated on a clean crank to turn around a tree.

Preferably, the effective length of the connecting rod is equal to the effective length of the crank, and the stroke of the pistons is equal to four times said effective length. Means are provided to avoid, during start-up, immobilization at mid-stroke of the rod. These means may include an extension of each connecting rod beyond the articulation on the crank, this extension being in particular equal to the effective length, and abutment means, provided on the crankcase, so that the end of the extension comes to bear against these stop means at mid-stroke of the rod. Advantageously, a connecting rod and a crank are provided on each side of the rod. The two connecting rods can be synchronized either by joining with the axis which then pivots in the piston connecting rod, or by forming with the axis a single piece, the connecting rod then being made up of two parts connected together around the axis of rotation.

Preferably, the crank is constituted by a radial zone of a wheel rotatably mounted around a shaft parallel to the axis of articulation of the connecting rod, this wheel carrying a pin for said rod, the zone between the pin and the axis of rotation of the wheel constituting the above crank.

When two wheels are provided, they are advantageously located on each side of the rod and are provided with a toothing capable of cooperating with a toothing of pinions fixed in rotation on an output shaft. Power is then transmitted by half on each side, thus balancing the mechanical assembly.

Due to the rectilinear displacement of the connecting rod, the compartment under piston from the central casing compartment comprising the mechanism can be very easily separated by a partition, provided with a seal. The engine then comprises suction compartments separated from a casing containing the connecting rod assembly by a wall traversed in a sealed manner by the connecting rod between the pistons.

Preferably, the engine comprises means (fan or compressor) to assist the filling of the suction compartments before precompression and admission into the combustion chamber.

The engine may include means for cooling the air before it is transferred to the combustion chambers. The cooling of the engine can be ensured by a circulation of water in the zone of the cylinders close to the cylinder heads and by air circulation in the zone of the cylinders distant from the cylinder heads.

The pistons may include valves provided on openings passing through each piston for the admission of air into the combustion chamber; advantageously, these valves are opening mechanically controlled upon arrival at bottom dead center and held magnetically.

The invention also relates to an internal combustion engine comprising means for self-injection of fuel, these self-injection means being able to be used independently or in combination with the characteristics defined above.

According to this other aspect of the invention, an internal combustion engine, in particular as defined above, is characterized by the fact that it includes means for self-injection of fuel controlled by the increase in pressure of the gases in the combustion chamber.

Preferably, the self-injection means comprise a small piston subjected to the pressure in the combustion chamber, this small piston being mounted to slide against elastic return means, in a chamber of an injector holder, this piston being linked to an injection needle which can move slidingly in a chamber receiving the liquid fuel through a non-return valve, the injection needle being provided, at its end facing the combustion chamber, with at least one injection nozzle, the assembly being such that when the pressure of the gases in the combustion chamber reaches a value sufficient to push the small piston against the elastic means, the injection needle is itself pushed back into the chamber containing the liquid fuel, which causes the injection of fuel, at a pressure adjusted by a needle rod and a spring.

The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be more explicitly discussed below in connection with an exemplary embodiment described with reference to the attached drawings, but which is by no means limiting.

Figure 1 of these drawings is a schematic axial section of an internal combustion engine according to the invention. Figure 2 is a simplified section along line II-II, Figure 1. Figure 3 is a section along line III-HI, Figure 1.

Figures 4 to 8 are diagrams illustrating the kinematics of the crankshaft of the engine.

Figure 9 is an enlarged section of a self-injecting fuel device.

Figure 10, finally, is a diagram of an alternative embodiment of the rods.

Referring to Figures 1 to 3, we can see an internal combustion engine 1 capable of operating in a two-stroke cycle, which has two opposite cylinders 2a, 2fc coaxial.

According to the representation of Figure 1, the axis of the cylinders is horizontal.

Preferably, the cylinders 2a, 2 are symmetrical with respect to a vertical median plane V. The ends of the cylinders 2g, 2fe remote from the median plane V are open. These ends are closed by a respective cylinder head 3â, 3k fixed, for example, either by means of screws, on a flange surrounding the end of the cylinder, or by tie rods connecting the two cylinder heads. Exhaust valves 4 are provided in each cylinder head, the number and dimensions of these valves being chosen so as to ensure the most efficient evacuation of the combustion gases.

The ends of the cylinders 3a, 3fc closest to the median plane V are connected by a casing 5.

In each cylinder is mounted a respective piston 6a 6 capable of sliding, in a reciprocating rectilinear movement, in the associated cylinder.

The pistons 6a, 6 & of the two opposite cylinders 2g, 2 are connected to each other by a rigid rod 7, advantageously rectilinear, arranged along the common axis of the cylinders 2a, 2b. The rod 7, preferably of circular section as visible in FIG. 2, can be rigidly fixed, at each of its ends, to the respective piston 6a, 6k. It is also possible to provide a connection between the ends of the rod 7 and the pistons 6a, 6k leaving a certain angular and transverse freedom between the rod 7 and the pistons so as to absorb any slight misalignment of the axes of the cylinders 2a, 2; it suffices that the connection between the pistons and the rod 7 is ensured in the direction of the axis of the cylinders. An articulation 8, orthogonal to the axis of the rod 7, is provided, preferably at mid-length of the rod 7. This articulation 8 is constituted by an axis 9 passing through a transverse diametral bore formed in the rod 7. The axis 9 extends beyond each side of the rod 8; the ends of this shaft 9, projecting relative to the contour of the rod 7, serve as articulations for a rod end respectively 10â, 10b, provided on each side of the rod 7. The two rods are parallel and located in a plane orthogonal to axis 9.

The rod 7 may be in one piece traversed by a bore for the axis 9, or be made in two parts connected together around the axis 9; in the latter case, the connecting rods 10a, IOJ2 can form a single part with the axis 9.

The end of each connecting rod 10â, 10b, distant from the axis 9, is articulated on a pin 11a, Hb carried by a corresponding crank 12â, 12b suitable for turning around a shaft 13â, 13b parallel to the axis d hinge 9 of the connecting rod on the rod. The shafts 13 _â , 13b are aligned and are located in the median plane V. The rod 7 passes between the shafts 13â, 13b-

In the embodiment shown, each crank 12a, 12b is constituted by a radial zone of a complete wheel 14 _â , 14b centered on the corresponding shaft 13â, 13b. Each wheel 14â, 14b is provided, on its periphery, with a toothing 15 which meshes with a conjugate toothing of a pinion 16a, 16b fixed in rotation on a shaft 17 parallel to the shafts 13a, 13b • This shaft 17, mounted rotatably in the casing 5, projects from at least one side of the casing and constitutes the output shaft of the engine. The connection in rotation by the pinions 16â, 16b ensures the transmission of power equally and a synchronization of the movement of the connecting rods and cranks.

Synchronization can be better ensured by securing the two connecting rods 10a, 10b with the axis 9, or making a single piece of 9, 10a, 10b, the rod 7 being produced in these cases in two parts connected together so to constitute a median plane bearing of the conventional type.

As visible from Figure 2, the connecting rods 10a, 10b are located between the wheels 14a, 14b. The stroke of the pistons 6g, 6b is equal to four times the effective length t of a connecting rod or a crank, as will be explained later in detail with reference to FIGS. 4 to 8. The effective length r is the distance between the geometric axes of articulation of the ends of each connecting rod and crank.

Cross partitions 18â, 18b are provided to close the cylinders 2â, 2b on the side opposite to the cylinder heads and to separate the suction compartments 19â, 19b relative to the interior volume of the casing 5, in which are the connecting rod / crank systems and the pinions 16â , 16b fixed on the output shaft 17. The casing 5 is either lubricated with an oil bath 5g at the bottom, or preferably of the dry sump type, the oil being taken up at the bottom by a pump, supplying oil under pressure the joints as well as the lubrication of the pistons between segments. The rod 7 passes through the partitions 18â, 18b in a sealed manner thanks to a lining 20 provided between each partition and the rod 7, driven by an alternating rectilinear movement.

The filling of the compartments 19â, 19b at the suction can be assisted by a fan or blower W or a compressor delivering fresh air into the inlet pipe 21s, 21b-

An inlet pipe 2 there, 21b opens into the corresponding suction compartment, in the vicinity of the partition 18â, 18b-

An air / air exchanger assembly E, comprising two exchangers Ea, Eb, assigned to the cylinders 2â, 2b is advantageously provided. The exchanger Ea comprises a tube Ia connected to the compartment 19a, in the vicinity of the partition 18a. The tubing ia has an area provided with cooling fins 22. On either side of the area of the fins 22, the tubing ta is connected by branches ≤a, na, with a capacity Câ of adjustable volume, for example using a piston Kâ, the position of which can be modified using adjustment means J.

The arrangement of the Eb exchanger is similar. The adjustment means J allow the pistons Ka, Kb to be moved simultaneously so as to modify the capacities Ca, Cb in the same way. As explained in detail below, the exchangers Eâ, Eb are alternately traversed by the air sucked in and then compressed before its transfer into the combustion chambers. This allows greater efficiency in cooling the air before transfer. The variable capacities Ca, Cb make it possible to modulate the quantity of air before its transfer and thus to adjust the fresh air / fuel ratio.

Each tube is equipped with a suction valve 23, diagrammatically shown, capable of opening to let air coming from outside, in the direction of arrow F, towards the chamber 19a or 19b. The valve 23 closes for a movement of gas in the opposite direction produced during a movement of the piston causing a reduction in the volume of the suction chamber.

Advantageously, valves 24 are provided on openings p passing through each piston 6g, 6b- These valves 24 allow the passage of compressed air from a suction chamber 19â, 19b to a working chamber B (or combustion chamber ) located between the piston and the cylinder head. The valves 24 open mechanically when the pistons reach bottom dead center; they can be kept open by magnetic attraction, their closing being done as soon as the pistons 6g, θ & start again. The valves 24 remain closed throughout the compression-combustion cycle. One could provide, in place of the valves 24, transfer lights, conventional in two-stroke engines, for passing air from the suction chamber to the combustion chamber. Cooling means for the cylinders 2â, 2b are provided. Advantageously, the part of the cylinders 2â, 2b close to the casing 5 is air-cooled, while the part of these cylinders close to the cylinder heads 3a, 3b is surrounded by a jacket 25â, 25b for the circulation of cooling water . The fuel supply to the working chambers B is preferably provided by an auto-injection device 26, housed in each cylinder head, for example in the central zone, and illustrated in more detail in FIG. 9.

This device comprises a small piston 27 slidably mounted in a chamber L of an injector holder P, meeting a compression spring 28 forming elastic return means. The injector holder P is fixed for example by screwing in a threaded housing M of the cylinder head which opens in the working chamber. The head of the small piston 27 has, in its center, an opening through which a hollow injection needle 29 passes. This needle 29 is integral with the piston 27 and has a central channel opening axially, on the side opposite the piston 6g or 6b, in a chamber 30 receiving the fuel. The end of the needle 29, which projects slightly beyond the head of the small piston 27, is provided with calibrated nozzles 31 of small diameter intended to ensure the injection of fuel. The axes of these nozzles are inclined at appropriate angles relative to the axis of the injection needle 29 which can slide in a bore 32a of a part 32 screwed into the injector holder P and comprising the chamber 30.

This chamber 30, at its end remote from the needle 29, has an orifice 33 for communication with a fuel inlet pipe. The orifice 33 is provided with a non-return valve 34 which allows the entry of fuel into the chamber 30 but opposes the reflux of this fuel from the chamber 30 towards the inlet pipe.

A needle rod 35 passes through the valve 34 and its point closes the internal orifice 37 of the channel of the needle 29, under the action of a spring 36 whose calibration regulates the injection pressure. The spring 36 works in compression is in abutment at one end against a stop secured to the rod 35 and, at another end (not visible) against a stop secured to the part 32. The needle rod assembly 35 is guided in part and other of the orifice 33 so as to ensure the proper functioning of the valve 34 which slides on the needle rod, a spring which can assist rapid closure.

The operation of this self-injection device is as follows. When the piston 6a or 6b of the working chamber associated with the self-injection device considered, compresses the gases, from a certain pressure, the small piston 27 will be pushed back by the pressure of gas against the spring 28 whose taring is predetermined. The recoil of the piston 27 causes the recoil of the injection needle 29 linked to this small piston 27. The entry of the injection needle 29 into the chamber 30, filled with fuel, causes a rise of the pressure of this fuel due to the reduction in volume created by the entry of the needle 29. The valve 34 will close and the pressure of the fuel in the chamber 30 increases until reaching a value sufficient to repel the needle rod 35 by compressing the spring 36, and open the orifice 37 to allow injection by the nozzles 31.

The injected fuel ignites on contact with compressed gases at high temperature.

The amount of fuel injected is adjusted by adjusting the displacement stroke of the small piston 27 of the self-injection device and therefore of the needle 29. This adjustment can be carried out in different ways, either by acting on the position of the injector holder P, or directly on the position of the small piston 27. To obtain rapid filling of the injection chamber 30, the injector is supplied with fuel under adjustable and controlled pressure. The operation of the valve 34 is instantaneous on closing as on opening due to the sliding of the needle rod 35. It is possible to act on the spring 36 to adjust the injection pressure. It also promotes the return to the initial position of the small piston 27 and the needle 29 and it ensures the filling of the chamber 30 without introduction of parasitic air bubbles.

One can act on the tension of the spring 28 to anticipate the start of injection.

Self-regulation occurs with the acceleration of the engine rotation speed because the pressure in the cylinders 2a, 2b increases with the displacement speed of the pistons 6â, 6b-

During starts, the pressure may be insufficient, one can then use a mechanical contact of the pistons 6a, 6b to drive the small piston 27 on a reduced stroke. The overall operation of the engine 1, in particular from the kinematic point of view, is as follows.

We will start from the top dead center position of the piston 6g for which the connecting rod 10a is aligned with the crank 12a, as illustrated diagrammatically in FIG. 4, on the side of the cylinder head 3a relative to the shaft 13a. The explanations given for connecting rod 10â / crank 12â also apply to connecting rod 10b / crank 2b.

The suction chamber 19â has reached its maximum volume and is therefore filled with fresh air which has been admitted by the pipe 2 there. The chamber 19b, on the other hand, is at its minimum volume and is at the start of suction.

The displacement of the piston 6a takes place from left to right, according to the representation of the figures, as a result of the combustion and the expansion of the gases in the working chamber situated to the left of this piston 6â. The rod 7 and the axis 9 move with the piston so that the hinge pin 11a between connecting rod and crank will move transversely from the axis of the rod 7 to describe a circle centered on the shaft 13a as illustrated in FIG. 5. Due to the equality of the effective lengths r of the connecting rod and of the crank, the triangle formed, in FIG. 5 and in FIG. 7, by the connecting rod 10a and the crank 12â and by the axis of the rod 7 is an isosceles triangle whose base is located on the axis of the rod 7.

Either due to the action of a starter, or by inertia, the pin 11a rotates around the shaft 13a in a determined direction, for example the clock direction according to FIGS. 4 to 8.

The law of displacement g of the pistons is defined by the formula: e = 2r (1 - cos), a designating the angle of the crank with respect to the axis of the rod 7 (see FIG. 5). The speed is zero when α = 0 or x and is maximum for α = τ / 2 or 3 τ / 2. At the middle of the stroke of the pistons 6a, 6b, each connecting rod is superimposed on the corresponding crank, at right angles to the rod 7 as illustrated in FIG. 6.

The piston 6a continuing its stroke, the axis 9 exceeds the alignment of the shafts 13a, 13b as illustrated in FIG. 7 and the compass formed by the connecting rod 10a and the crank 12a opens in the other direction.

At the bottom dead center of the piston 6a (FIG. 8), the connecting rod 10a is aligned with the crank 12a in the opposite direction to that of departure.

The stroke of the pistons 6a, 6b is therefore equal to 4r. In its stroke from left to right, the piston 6a has compressed the air trapped in the suction chamber 19a and, when the pressure in the chamber 19 becomes sufficient, towards the end of the stroke of the piston 6a, the fresh air is transferred from the chamber 19 to the working chamber B due to the fact that the valves 24 open, and from the pressure difference . During the return stroke of the piston 6g, the crankpins lia,

11b will describe the lower semicircle completing the upper semicircle of FIGS. 4 to 8, which makes it possible to find the configuration of FIG. 4, at the end of the return stroke.

The exhaust valves 4 open at the end of the stroke of the piston 6a to allow the evacuation of the combustion gases and close again as soon as the piston 6a starts again towards its top dead center so as to allow the compression of the fresh air. which was introduced into the working chamber.

At the end of compression, the fuel is self-injected and the cycle continues.

The phases at the suction chamber 19b and the working chamber limited by the piston 6 are offset by 180 ° with respect to those considered previously.

The wheels 14â, 14b are permanently subjected to the driving action of one or the other piston which gives a good regularity of the torque obtained.

The exchangers Eâ, Eb operate as follows.

When the rod 7 moves from right to left, the chamber 19a is in suction and the corresponding valve 23 is open. The pressurized air supplied by the blower fills the chamber 19â, the exchanger Eâ and the modular capacity Câ.

After passage from the left dead center, the movement of the rod 7 and of the pistons 6g, 6b is reversed for a movement from the left to the right. The piston 6â compresses the air in the chamber 19â, whose associated valve 23 has closed. The air is discharged into the exchanger Ea and into the modular capacity Câ- The air pressure increases as a function of the residual volume of the exchanger Ea and of the capacity Câ-

A little before arriving at the right neutral position, the exhaust valves 4, associated with the piston 6g open, as do the valves 24 of this piston 6a. The compressed and cooled air in the exchanger Eâ is quickly transfers through the piston 6g and scans the corresponding combustion chamber.

It is possible to adjust the amount of air depending on the amount of fuel in each cycle. You can adjust the pressure and flow rate of the blower W which feeds the chambers 19â, 19b at the suction.

When the modular capacity Câ, Cb is set to its maximum value, a maximum of air is introduced, on the other hand the pressure for transferring the air to the combustion chamber will be lower.

If the quantity of air to be transferred is reduced, for example by reducing the volume of the modular capacity, the sweeping is reduced and part of the burnt gases is preserved, which corresponds to a recirculation effect recommended for engines during revs operating requiring little fuel.

When starting, the output shaft 17 is driven by a starter, the pistons 6g, 6b not yet having a propelling action. The position corresponding to the half of the piston 6â, 6b stroke, position for which each connecting rod is superimposed on the corresponding crank while the axis 9 is aligned with the shafts 13a, 13b, can be critical.

In fact, if the speed of the moving assembly is insufficient, this crew can come to a stop midway and the connecting rods

10â, 10b can rotate around the axis 9, aligned with the shafts 13â, 13b, without the connecting rods driving the rod 7 and all of the movable assembly.

To avoid this, as illustrated in FIG. 10, the connecting rods 10â, 10b are extended, beyond the pins 11a, Hb of a length equal to the effective length r up to an end such as 10c_.

With such a geometry, the end such as 10s of the connecting rods will describe a straight line H orthogonal to the axis of the rod 7, and passing through the center of the circle described by the pin 1 there.

A stop D is provided on the motor casing so that the end 10c. comes to bear against this stop D at mid-stroke of the rod 7. The stop D is placed so as to tilt the connecting rod 10â, under the action of the journal lia, so that the compass formed by the branches 10â, 12â, after having completely closed in the mid-stroke position, is redeployed with the branch 12â being crossed by the branch 10â , as illustrated by the dashed position in Figure 10. A symmetrical stop of the stop D with respect to the center

13a is provided, although it is not shown in this figure 10.

Each stop D can be constituted by a rotary axis which can be erased when the engine operates by itself under the action of burnt gases or compressed air. The engine of the invention can operate on various fuels. It has a high yield with reduced pollution. The expansion and compression of the gases is carried out directly without passing through a crankshaft.

The synchronization of the movement and the good transmission of power are ensured by the pairs of gears constituted by the wheels 14â, 14b and the pinions 16â, 16b-

The system being symmetrical, the speed setting and braking of the mobile crew are identical. The weight of this crew (set of pistons 6g, 6b, rod 7 and connecting rod assembly) can be reduced. Indeed, the linear movement avoids subjecting the pistons 6â, 6 to transverse forces so that the sliding guide of the pistons in the cylinders does not require guide skirts of a significant axial length, and the height of the pistons can be reduced. Because of its lightness, this type of engine can equip all mobile assemblies including aircraft, ULM in particular.

The gas path is improved thanks to the separation of the air intake compartments under the pistons and the casing, which accelerates the sweeping of the combustion gases. This results in a decrease in pollution. The pistons 6â, 6b are lubricated by pressurized oil distributed between two scraper segments, not visible in the drawings or inside a single scraper segment.

Sealing on the burnt gas side is ensured by segments, in a conventional manner. By avoiding the use of lights in the sleeves for sweeping and transferring gases, it improves the longevity of the assembly and reduces oil consumption and pollution.

There are operating conditions which are substantially those of a four-stroke engine.

The number of exhaust valves 4 can be increased to improve the speed of the evacuation of the burnt gases.

The cooling of the intake air, for example by the fin system 22, improves the conditions for supplying fresh air and the quantity of air admitted even at low speed; this increases the admissible quantity of fuel and the low-speed torques and the efficiency.

The calories evacuated at the fins 22 are at a low temperature level, which improves the cooling conditions by the interior of the pistons and of the liners.

The engine can, of course, have several pairs of opposing cylinders, although the description has concerned an example of an engine with a single pair of cylinders.

The architecture of the engine which is the subject of the invention is organized around the crankshaft allowing the linear displacement of the mobile assembly consisting of two pistons linked by a rigid rod in opposite coaxial cylinders.

This makes it possible to separate from the central housing, containing the rod-crank assembly necessary for the transformation of the reciprocating rectilinear movement into continuous rotary movement, the compartments under piston serving for the suction and the precompression of the air before its transfer into the motor combustion chambers.

This allows the air to be isolated from the lubricated parts, thus avoiding the usual pollution of two-stroke engines. The transfer of air directly through the pistons also eliminates the problem of segments passing in front of lights.

The exhaust through the cylinder heads placed at the ends of the engine also makes it possible to dimension the corresponding valves widely. The axial scanning is thereby activated without resorting to high pressures, the pressure drops on the air and on the exhaust being able to be reduced in significant proportions.

This very simple architecture allows: 1 ° l to reduce the weight of the pistons and connecting rods and to reduce friction due to the guidance carried out directly by the pistons moving linearly in the coaxial cylinders and the fact that all internal power exchanges, compression, acceleration and braking are carried out directly through the straight piston connecting rod.

Only the mechanical power available travels through the crank rod system.

2 ° / reduce the weight of blocks and housings

3 ° / to maintain in the central part of the engine temperatures close to ambient temperature by cooling by air / air exchanger thus reducing the temperature of the air before its transfer and its strong compression in the combustion chambers. This reduces the power absorbed by this compression.

4 ° / to regulate the quantity of air transferred in a simplified manner due to the low pressure losses of the intake and exhaust circuits. The powers put into play are thus reduced. For the adjustment, the air is more or less boosted at the intake and / or a modular capacity is acted upon making it possible to modify the precompression ratio in the chambers under piston. It is thus possible to adjust to all rotation speeds the amount of air transferred as a function of the amount of fuel to be burned in each cycle, as a function of the torque requested. We can thus increase the torque at low speed and reduce pollution. In addition, recirculation of exhaust gases can be avoided by reducing the amount of air transferred.

Direct self-injection of fuel promotes efficiency and further simplifies the architecture of the engine and electrical and electronic control further reduces pollution.

The temperature control in the hot part: top of cylinder and exhaust cylinder heads, guarantees good combustion. In general, the architecture of the engine allows many parameters to be easily adjusted, thereby increasing efficiency and reducing pollution.

Claims

CLAIMS 1. Internal combustion engine, in particular with a two-stroke cycle, comprising at least two opposite cylinders, coaxial, and, in each cylinder, a reciprocating rectilinear piston, a connecting rod / crank system being provided to transform the movement of each piston in a circular movement of an output shaft, characterized in that the pistons (6â, 6b) of two opposite cylinders (2â, 2b) are connected to each other by a rigid rod (7) animated by the same reciprocating rectilinear movement as the pistons, and that at least one articulation (8), orthogonal to the axis of the rod (7), is provided on this rod (7) for the end of a connecting rod ( 10â, 10b), the other end of this connecting rod being articulated (11a, 11b) on a crank (12â, 12b) suitable for turning around a shaft (13â, 13b).

2. Engine according to claim 1, characterized in that the effective length (r) of the connecting rod is equal to the effective length of the crank, and the stroke of the pistons (6g, 6b) is equal to four times said effective length (r).

3. Engine according to claim 2, characterized in that it comprises means (10c, D) to avoid, during startup, immobilization at mid-stroke of the rod (7).

4. Motor according to claim 3, characterized in that the means for preventing immobilization at mid-stroke comprise an extension of each connecting rod (10â, 10b) beyond the articulation (lia, Hb) on the crank (12a, 12b), this extension being in particular equal to the effective length (r), and stop means (D) provided on the motor casing so that the end (10c) of the extension comes to bear against these stop means (D) at mid-stroke of the rod (7).

5. Motor according to one of the preceding claims, characterized in that a connecting rod (10â, 10b) and a crank (12â, 12b) are provided on each side of the rod.

6. Engine according to claim 5, characterized in that the connecting rods (10â, 10b) form with the axis (9) a single piece.

7. Motor according to one of the preceding claims, characterized in that the crank (12â, 12b) is constituted by a radial zone of a wheel (14â, 14b) rotatably mounted around a shaft (13â, 13b) parallel to the articulation axis (9) of the connecting rod (10â, 10b), this wheel (14â, 14b) carrying a pin (11a, Hb) for said connecting rod, the area (12a, 12b) between the pin (11a, Hb) and the axis of rotation of the wheel (14a, 14b) constituting the said crank.

8. Motor according to claims 5 and 7, characterized in that the two wheels (14â, 14b) located on each side of the rod (7) are provided with a toothing (15) capable of cooperating with a toothing of pinions (16â, 16b) fixed in rotation on an output shaft (17) parallel to the axis of rotation of the wheels.

9. Motor according to one of the preceding claims, characterized in that it comprises suction compartments (19â, 19b) separated from a casing (5) containing the crankshaft (10â, 10b, 12â, 12b) by a wall (18â, 18b) traversed in a sealed manner by the rod (7) connecting the pistons (2â, 2b).

10. Engine according to claim 9, characterized in that it comprises means (fan or blower W or compressor) to assist the filling of the suction compartments (19a, 19b) before precompression and admission into the combustion chamber ( B).

11. Engine according to any one of the preceding claims, characterized in that it comprises means for cooling (22, Eâ, Eb) of the air during the precompression before transfer to the combustion chambers.

12. Engine according to any one of the preceding claims, characterized in that it is cooled by a circulation of water (25â, 25b) in the region of the cylinders (2â, 2b) close to the cylinder heads (3â, 3b) and by air circulation in the cylinder area away from the cylinder heads.

13. Engine according to any one of the preceding claims, characterized in that the pistons include valves (24) provided on openings (p) passing through each piston (6g, 6b) for the admission of air into the chamber combustion, these valves being mechanically controlled opening upon arrival at bottom dead center and magnetically maintained.

14. Internal combustion engine, according to any one of the preceding claims, characterized in that it comprises self-injection means (26) controlled by the increase in pressure of the gases in the combustion chamber (B ).

15. Engine according to claim 14, characterized in that the self-injection means (26) comprise a small piston (27) subjected to pressure in the combustion chamber (B), this small piston being slidably mounted at against elastic return means (28), in a chamber (L) of an injector holder (P), this piston (27) being linked to an injection needle (29) which can move by sliding in a chamber (30) receiving the liquid fuel through a non-return valve (34), the injection needle (29) being provided, at its end facing the combustion chamber, with at least one injection nozzle (31), the assembly being such that when the gas pressure in the combustion chamber (B) reaches a value sufficient to push the small piston (27) against elastic means (28), the needle d the injection (29) is itself pushed back into the chamber (30) containing the liquid fuel, which causes the injection of comb ustible, at a pressure adjusted by a needle rod (35) and a spring (36).

LOCATION (RULE 26)